Rotating spectrographic electrode holder



Aug. 7, 1956 H. TODD 2,758,238

ROTATING SPECTROGRAPHIC ELECTRODE HOLDER Filed July 23, 1952 2 Sheets-Sheet 1 Aug 7, 1956 H. TODD ROTATING SPECTROGRAPHIC ELECTRODE HOLDER Filed July 23, 1952 2 Sheets-Sheet 2 hwntm': Hf/VQY 7000,

United States Patent O 1 2,758,238 ROTATING 'SPECTROGRAPHIC ELECTRODE HOLDER Henry Todd, Monongahela, Pa., assigner to United States Steel Corporation, a corporation of New Jersey Application July '23, 1952, Serial No. 300,408 7 Claims. (Cl. S13- 149) The present invention relates in general to the art of spectroscopy and more particularly to a rotating electrode holder especially suitable for a spectrograph.

Although spectrographic analysis` has now become commonplace in modern industry, these are some disadvantages that remain inherent in its use. One of the disadvantages of using the spectrograph for quantitative analyses is the very small amount of the sample that may be used in each actual analysis. Up to the time of my invention, the apparatus and method most generally used for spectrographic analyses involved the use of two fixed electrodes, one of which was the sample being analyzed and the other the so-called counter carbon electrode, and an arc struck between the two fixed electrodes. With this arrangement the resultant arc, which is struck between the electrodes, is confined to one particular location on the sample. The fact that the spot burned by the electric arc or spark may not be truly .representative of the sample is an ever present possibility. l propose to eliminate this disadvantage by providing an electrode holder which may be rotated so that the struck arc or spark may be directed to the entire surface at the end of the sample electrode thereby utilizing the entire end surface of the sample for the analysis.

Accordingly, it is an object of my invention to provide a rotating electrode holder which may be attached to a spectrograph to enable the struck arc to impinge against the entire end surface of the sample electrode in the course of the analysis.

This and other objects will become more apparent after referring to the following specification and attached drawings, in which:

Figure l is a plan view;

Figure 2 is an elevational View partly in section;

Figure 3 is an enlarged cross-sectional detail View of the holder of the invention;

Figure 4 is a plan view of the electrode holder block of the invention;

Figure 5 is a side elevation of Figure 4;

Figure 6 is an end view of Figure 4;

Figure 7 is an enlarged cross-sectional detail View of the holder of the invention showing an adaptor electrode holder; and

Figure 8 is a View similar to Figure 7 showing a second type of adaptor.

Referring more particularly to the drawings, reference numeral 2 indicates generally a spectrograph having the rotating electrode holder of my invention incorporated therein. The spectrograph 2 consists essentially of a base 4 which supports an arc-spark of Petri stand 6. The upper portion of the arc-spark stand is surrounded by a sheet metal box or enclosure 8 which serves as a shielding or protective member for the upper portion of the arc-spark stand. A cover 10 may be applied on the top of the enclosure 8 if desired. Screw 12 with nuts 14 provides vertical adjusting means for the stand.

The upper portion of the arc-spark stand consists of two steel plate members 16 and 18 which are vertically spaced apart and electrically insulated from each other by means of spacing posts 20 which may be made of micarta or similar insulating material. The unit consisting of the plate 16 and 18 and spacing posts 20 may be mounted on a micarta column 22 which insulates the unitfrom the metal box 8. Suitable electrical leads 24 and 26 are connected to the plates 16 and 18 respectively.

Patented Aug. 7, 1956 The apparatus thus far described is conventional, except for the rotating electrode holder of my invention the details of which will now be described.

The rotating spectrographic electrode holder of my invention consists of a hollow spindle 28 rotating in a bearing 30. The top of the spindle is provided with an integral machined head 32 containing a split collect type chuck 34 having adjustable jaws 36 in its upper portion. The hollow neck 38 of the chuck 34 iits into the bore 40 of the spindle 28 so that when an electrode is held by the chuck, the bottom portion thereof will extend into the bore of the spindle. The head 32 of the spindle lits over a main housing or body 42 which encases the bearing 30. The housing has a slotted projection 44 adjacent its bottom on one side by which it is fastened onto the edge of the plate 18 of the Petri stand 6 by means of a clamping screw 46. The lower part 48 of the spindle projects below the housing and is titted with a pulley 50 which is preferably grooved for accommodating one end of an endless drive belt 52, the other end of which is fitted around the pulley 54 of a motor 56. A hole 58 is provided in the enclosure beneath and in line with the bore of the spindle 28. A bearing or gland 60 having a threaded bore 62 is aiiixed to the underside of the enclosure 8 with its bore in alignment with the hole S8 by means of screws 64. An adjustable screw 66 having a knurled handle 68 on one end is threaded into the bore 62 and projects through the hole 58 into the bore 40 of the spindle for vertically adjusting an electrode being held in the chuck and spindle.

A steel block 70 having a vertical hole 72 in one end is slidably mounted for horizontal movement on the upper plate 16. The steel block 70 is adjustably positioned on the plate 16 with a portion thereof overhanging the edge of the plate. The vertical hole 72 is in the end of this overhanging portion. The block 70 is positioned on top of the plate 16 and is made to slide thereon by means of slots or grooves 74 which are machined in the upper surface of the plate 16 and receive rectangular guide members 76 which depend from the underside of the block 70. A graduated scale 78 on the side of the steel block 70 cooperates with an indicating mark 80 on the side of the plate 16 for determining the position of the hole 72 relative to the axis of rotation of the spindle 28. A spring-loaded ball 82 is provided in the end of the body of the block 70 adjacent the hole 72 for holding an electrode therein.

ln operation, the sample X to be analyzed in the spectrograph is machined to a round shape having a diameter of approximately 1/2 inch and then inserted in the chuck 34 with one end iitting into the bore 40 of the spindle 28 and resting on the end of the adjusting screw 66. The other end of the sample extends upwardly above the chuck 34. The steel block 70, containing a counter carbon electrode 84 in its vertical hole 72 with one end depending therefrom, is placed on the upper plate 16 and adjusted oli-center of the axis of the sample electrode X according to the amount of surface of the electrode blank desired to be traversed by the struck arc or spark during the analysis. After the spectrograph has been thusadjusted, the space between the twol electrodes is properly adjusted by means of the adjusting screw 66, and the motor 56 is actuated by means of a switch, not shown, to start rotation of the spindle 28. The spark gap is struck by introducing current to the plates 16 and 18 through the leads 24 and 26 while the spindle 28 is rotating.

in order to extend the rot-ating `principle to samples that cannot be rotated, due to size or shape, such samples are machined so as to have at least one side with a plain surface and are then positioned on top of the plate 16 in place of the steel block 70 as shown by the ice ysample in Figure 7. The` sample Y is placed on the plate 16 so as to overhang the edge thereof so that it is positioned directly above the chuck 34. In order that a surface of the sample Y vand not a point be utilized in the analysis, an adaptor electrode holder 86 having an eccentric electrode receiving bore 38 therein is inserted in the chuck 34. The counter carbon electrode 84 is held in the bore of the electrode holder by means of a springloaded ball 90 which is located in the side wall of the holder adjacent the bore 88. The amount of eccentricity of the bore 38 determines the degree of the circular path to be traversed by the arc between the sur-face of the sample Y and the counter carbon electrode 84.

ln Figure 8 I have shown a modified electrode holder 92 having a recess 94 in its upper end for carry-ing an electrode made up of compressed or briquetted material. The electrode holder 92 also fits in the chuck 34 and the bore of the spindle 28.

While one embodiment of my invention has been shown and described it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

l. A spectrograph comprising a base, a vertically disposed arc-spark stand mounted on said ybase, a pair of vertically spaced upper and lower arc-spark plates mount ed on the upper portion of said stand, an enclosure supported on said base and spaced from and surrounding said upper portion, an electrode holder block slidably mounted for horizontal movement on said upper plate with a portion thereof overhanging the edge of the upper plate, said upper plate having a pair of spaced parallel grooves in the upper surface thereof, said electrode holder block having a pair of spaced guide runners depending from the underside thereof adapted to fit and slide in said grooves, an electrode held by and depending from the overhanging portion of said holder block, a

main body member mounted within said enclosure on the lower plate and disposed below the overhanging portion of'said holder block, said mainbody member having a vertical center bore therethrough, a hollow spindle rotatably mounted in the `center bore of said main body member, achuck having adjustable work-holding jaws mounted on the upper portion of said spindle, said chuck being adapted to support electrode means in cooperative association with an electrode held in said electrode holder block, and means connected with said spindle for driving the same.

2. A spectrograph comprising a base, a vertically disposed arc-spark stand mounted on said base, a pair of vertically spaced upper and lower arc-spark plates mounted on the upper portion of said stand, an enclosure supported on said base and spaced from and surrounding said upper portion, an electrode holder block slidably mounted for horizontal movement on said upper plate with a portion thereof overhanging the edge of the upper plate, said electrode holder block having a vertical holo in the overhanging portion thereof for receiving an electrode, a spring loaded ball mounted within said electrode holder block adjacent said vertical hole with a circumferential portion thereof projecting into said hole for retaining an electrode therein, a main body member mounted within said enclosure on the lower plate and disposed below the overhanging portion of said holder block, said main body member having a vertical center bore therethrough, a hollow spindle rotatably mounted in the center bore of said main body member, a chuck having adjustable work-holding jaws mounted on the upper portion of said spindle, said chuck being adapted to support electrode means in cooperative association with an electrode held in said electrode holder block, and

means connected with said spindle for driving the same.

3. A spectrograph comprising a base, a vertically disposed arc-spark stand mounted on said base, a pair of vertically spaced .upper and lower arc-spark kplates mounted on the upper portion of said stand, an enclosure supported on said base and spaced from and surrounding said upper portion, an electrode block slidably supported on said upper plate with a portion 'thereof overhanging the edge of the upper plate, a main body member mounted within said enclosure on said lower plate and disposed below said electrode, said main body member having a vertical center bore therethrough, a hollow spindle rotatably mounted in the center bore of said main body member, a chuck having adjustable work-holding jaws mounted on the upper portion of said spindle, an elongated electrode holder having an eccentric electrode-receiving bore mounted in the jaws of said chuck with one end thereof inserted in the bore of said spindle and its other end projecting above said chuck toward the portion of said electrode block overhanging the edge of said upper plate, an electrode fitted in said eccentric electrode-receiving bore, means in said holder for releasably securing said electrode in said bore, and means connected with said spindle for rotating the same.

4. A spectrograph comprising a base, a vertically disposed arc-spark stand mounted on said base, a pair of vertically spaced upper and lower arc-spark plates mounted on the upper portion of said stand, an enclosure supported on said base and spaced from and surrounding said upper portion, an electrode holder block slidably mounted for horizontal movement on said upper plate with a portion thereof overhanging the edge of the upper plate, an electrodev held by and depending from the overhanging portion of said electrode holder block, a main body member mounted within said enclosure on the lower plate and disposed below the overhanging portion of said electrode holder block, said main body member having a vertical center bore therethrough, a hollow spindle rotatably mounted inthe center bore of said main body member, a chuck having adjustable work-holding jaws mounted on the upper portion of said spindle, said chuck being adapted to support electrode meansin cooperative association with an electrode held in said electrode holder block, and means connected with said spindle for rotating the same.

5. The combination as defined by claim 4 wherein an elongated electrode holder isinserted in said chuck, said elongated electrode holder having a recess in the upper end thereof for carrying an electrode element.

6. The combination as defined by claim 4 wherein the space between thework-holding jaws of said chuck cornmunicate with the bore of said hollow spindle, said enclosure having a hole therein beneath said hollow spindle and aligned with the bore of the latter, a bearing having a threaded bore mounted on said enclosure with its threaded bore communicating with the hole in said enclosure, and an adjusting screw threaded in said bearing bore and extending therefrom into the bore of said spindle for vertically adjusting an electrode supported by the chuck on the upper end of said spindle.

7. The combination as defined by claim 4 wherein an elongated electrode holder having an eccentric electrodereceiving bore is carried by said chuck with one end thereof inserted in the bore of said spindle and its other end projecting above said chuck toward the portion of the electrode holder block overhanging the edge of said upper plate, an electrode fitted in said eccentric electrodereceiving bore, and means in said holder for releasably securing said electrode in said bore.

References Cited in the file of this patent UNITED STATES PATENTS 905,666 Davis Dec. l, 1908 1,581,729 Gerdien et al. Apr. 20, 1926 2,324,899 Arthur July 20, 1943 2,344,719 Nusbaum et al. Mar. 21, 1944 2,346,512 Scribner etal. Apr. l1, 1944 

1. A SPECTROGRAPH COMPRISING A BASE A VERTICALLY DISPOSED ARC-SPARK STAND MOUNTED ON SAID BASE, A PAIR OF VERTICALLY SPACED UPPER AND LOWER ARC-SPARK PLATES MOUNTED ON THE UPPER PORTION OF SAID STAND, AN ENCLOSURE SUPPORTED ON SAID BASE AND SPACED FROM AND SURROUNDING SAID UPPER PORTION, AN ELECTRODE HOLDER BLOCK SLIDABLY MOUNTED FOR HORIZONTAL MOVEMENT ON SAID UPPER PLATE WITH A PORTION THEREOF OVERHANGING THE EDGE OF THE UPPER PLATE, SAID UPPER PLATE HAVING A PAIR OF SPACED PARALLEL GROOVES IN THE UPPER SURFACE THEREOF, SAID ELECTRODE HOLDER BLOCK HAVING A PAIR OF SPACED GUIDE RUNNERS DEPENDING FROM THE UNDERSIDE THEREOF ADAPTED TO FIT AND SLIDE IN SAID GROOVES, AN ELECTRODE HELD BY AND DEPENDING FROM THE OVERHANGING PORTION OF SAID HOLDER BLOCK, A MAIN BODY MEMBER MOUNTED WITHIN SAID ENCLOSURE ON THE 